New Japanese study below [1].
When I was diagnosed in 2004, it was already old news that PCa somehow reduces testosterone [T] production. In 1998, Patrick Walsh had published a Johns Hopkins study [2] of 63 men who had undergone prostatectomies. 12 months after surgery "there was a statistically significant increase in serum testosterone, free testosterone ...". The study was repeated by two other institutions, with similar results.
This certainly influenced my view of T as the presumed dangerous "fuel" for PCa.
There were also a few studies back then associating lower T with a poorer prognosis. One could look at those studies as an indication of hypogonadism being a risk factor for PCa, but the Walsh study turns that around. PCa becomes more aggressive when it somehow inhibits T production.
So one might expect T to ultimately increase after brachytherapy.
"Median pre-implantation {T was 418 ng/dL.}"
"{T} decreased significantly to a median nadir of 89.4% of baseline {372 ng/dL} occurring at 6 months, and then recovered to baseline at 18 months after {brachytherapy}."
i.e. brachytherapy itself lowers T. And, even at 18 months, recovery was only to baseline - not to the higher levels seen following prostatectomy. "Patients were followed for 24-60 months", but increases over baseline were not reported, at least in the Abstract.
The paper defines the cutoff for hypogonadism as 300 ng/dL, although 350 ng/dL is more common these days IMO.
"The group of patients whose {Ts} fell below {300 ng/dL} (biochemical hypogonadism) after {brachytherapy} started with lower baseline {Ts (median: 354 ng/dL)} than patients whose {Ts} did not fall below {300 ng/dL (median: 490 ng/dL)}."
-Patrick
[1] ncbi.nlm.nih.gov/pubmed/967...
[2] ncbi.nlm.nih.gov/pubmed/307...
Urology. 2019 Feb 1. pii: S0090-4295(19)30089-5. doi: 10.1016/j.urology.2019.01.022. [Epub ahead of print]
Testosterone Profiles after Brachytherapy for Localized Prostate Cancer.
Taniguchi H1, Kawakita S2, Kinoshita H2, Murota T2, Matsuda T2.
Author information
1
Department of Urology and Andrology, Kansai Medical University, Hirakata, Osaka, Japan. Electronic address: taniguhi@hirakata.kmu.ac.jp.
2
Department of Urology and Andrology, Kansai Medical University, Hirakata, Osaka, Japan.
Abstract
OBJECTIVE:
To evaluate patients' serum total testosterone levels (STLs) after brachytherapy (BT) for prostate cancer.
METHODS:
We enrolled 102 men who underwent permanent interstitial BT using I125 without androgen deprivation therapy for localized prostate cancer. Seed BT radiation dose was 145 Gy. Patients were followed for 24-60 months after BT. The primary outcome was STL kinetics after BT. Predictors of testosterone decrease were also analyzed.
RESULTS:
Median pre-implantation STL was 4.18 ng/mL. STL decreased significantly to a median nadir of 89.4% of baseline (3.72 ng/mL) occurring at 6 months, and then recovered to baseline at 18 months after BT. The group of patients whose STLs fell below 3.00 ng/mL (biochemical hypogonadism) after BT started with lower baseline STLs (median: 3.54 ng/mL) than patients whose STLs did not fall below 3.00 ng/mL (median: 4.90 ng/mL). The group of patients whose STLs decreased by more than 1.00 ng/mL over the study period had significantly higher median baseline STLs (median: 5.05 ng/mL) than the group whose STLs decreased by less than 1.00 ng/mL (median: 3.64 ng/mL).
CONCLUSIONS:
Although STL decreased significantly after I125-based BT, STL decline after treatment for localized prostate cancer was not large and recovered over time.
Copyright © 2019. Published by Elsevier Inc.
KEYWORDS:
Brachytherapy; Hypogonadism; Prostate cancer; Radiotherapy; Testosterone
PMID: 30716344 DOI: 10.1016/j.urology.2019.01.022